Rocket projectile



y 2, 1940- L. A. SKINNER 2,206,057

ROCKET PROJECTILE Filed Aug. 51, 1939 Fig] -1- L invenigi:

E A v I E 1; 598% l IT'LE r factured and used by or for Patented July 2,1940 srArsS PATENT FFlC ,206,051 nocxa'r raomc'rrw Leslie A. Skinner,United Calll'., assignor to the Government of the United States Army,Berkeley,

A ppllcation August 31, 1939, Serial No. 292,841 a cam (01. 102-23)(Granted under the act of amended April 30, 1928;

The invention described herein may be manuthe Government forgovernmental purposes, without the payment to me of any royalty thereon.

This invention relates to a rocket projectile.

In a projectile of the type shown in my Patent 1,994,490'of March 19,1935, an external propelling charge initiates the flight of theprojectile and an auxiliary propelling charge carried by theprojectile'iunctions during flight in the manner common to rockets tocontinue propulsion.

In pyrotechnic rockets employing black powder as a driving charge it hasbeen customary to employ a discharge orifice of a fixed size which has acertain definite relation to the speed at which the gases are liberatedin order that these gases should be forcibly expelled, thus lifting therocket by their impact with the air.

Where the driving charge consists 'of a composition, such asnitrocellulose or a double base powder, having the characteristics of arequirement of pressure to initiate ignition and an increased burningrate under pressure, it becomes necessary to provide a means forregulating or controlling the pressure within the driving chargecontainer.

The purpose of this invention is .to regulate the pressure and thevelocity of efliux of the gases by means of an exhaust orifice whichincreases in cross-sectional area as the driving charge is consumed.

' The specific nature of other objects and advantages thereof willclearly appear from a description of a. preferred embodiment as shown inthe accompanying drawing in which:

Fig. 1 is a view in side elevation in section of a rocket projectile.

Fig. 2 is a longitudinal sectional view of the discharge tube.

Referring to the drawing by characters of reference there is shown aprojectile comprising a body 5 having a partition 8. The space in frontof the partition is adapted to contain any desired element such as anexplosive, signalling, or incendiary charge I or it may be used to housea parachute or carry a message. The space in rear of the partitioncontains a driving charge 8 which preferably consists of nitrocelluloseor a double base powder which requires a certain amount of pressure toinsure ignition and whose burning rate increases as the pressureincreases.

A discharge tube 9 of a metal having a high melting point is attached tothe rear of the body and partly the invention as well as,

March 3, 1883, as 370 0- G.

and is formed with a forwardly flared entrance In and a rearwardlyflared exit passage ll to provide a constricted throat. The throat ofthe passage is further constricted by a lining I2 of a lowmelting pointmaterial such as Wood's metal, solder, Babbitt and the like. The liningwhich is similarly formed with a. forwardly flared entrance I; and arearwardly flared passage i l, extends rearwardly an appreciabledistance from the front edge of the entrance III of the tube. Thethickest part of the lining which establishes the constricted throat I5is positioned a relatively short distance from the front edge of theentrance lll, this distance being approximately equal to the radius ofthe tube and being substantially at the constricted throat of the tube.

The particular manner of igniting the driving charge forms no part ofthis invention but as an example it may be accomplished by conventionalmethods employed in rockets or as shown in the patent previouslyreferred to. At the commencement of combustion of the driving charge thequantity of gas developed will be small but because the throat I5 isrelatively small the pressure within the driving charge chamber willbuild up rapidly. when ignition is well established and the pressureincreases, the outrushing hot gases will cause the lining to be meltedand the molten metal will be forced rearwardly. In this manner thedischarge criflce will be gradually enlarged until the prederminedentrance IB and exit passage II is reached.

I claim:

1. A rocket comprising a body, a driving charge in the body, a tubefixed to the rear of the body, said tube formed of a metal having a highmelting point and having a forwardly flared entrance and a rearwardlyflared exit passage to provide a constricted throat, a lining of a lowmelting point metal in the tube with its thickest portion spaced fromthe front edge of the tube and having a forwardly flared entrance and arearwardly flared passage to provide a constricted throat.-

, 2. A- rocket comprising a body, a. driving charge in the body, a tube'of a high melting point metal flxed to the rear of the body, a liningof a low melting point metal in the tube, said lining having itsthickest portion spaced from the front edge of the tube and having aforwardly flared entrance and a more gradual rearwardly flared passageto provide a constricted threat.

3. A rocket comprising a body, "a driving charge in the body, a tube ofa high melting point metal flxed tothe rear of the body, a lining of alow melting point metal in the tube, said lining having its thickestportion spaced from the front edge 01 the tube and having a forwardlyflared entrance and a rearwardly flared passage to provide' a.constricted throat.

4. A rocket comprising a body, a driving charge in the body, a tubeofahigh melting point metal fixed to the body, and a lining of a lowmelting point metal in the tube and having a constricted throat spacedfrom the front edge of the tube.

5. A rocket comprising a body, a driving charge in the body, a tube of ahigh melting point metal fixed to the body, and a lining'of a lowmelting point metal in the tube and having a constricted throat.

.6. A rocket comprising a body, a driving charge in the body, a tube ofa high melting point metal fixed to the body and having a constrictedthroat spaced from the entrance end, and a lining of a low melting pointmetal in the tube and having a constricted throat in the throat-ofthetube.

'7. A rocket comprising a body, a' driving charge in the body, a tubefixed to the body, and a lining in the tube removable by heat, saidliner having asharply flared entrance and a gradually flared exitpassage providing a constricted throat.

8. A rocket comprising a body, a driving charge in the body, a tubefixedto the body, and a lining in the tube removable by heat, said linerhaving a fiared'entrance and a flared exit passage providing aconstricted throat...

' LESLIE A. SKINNER.

